Ti3C2T and Mo2TiC2T MXenes as additives in synovial fluids - towards an enhanced biotribological performance of 3D-printed implants

• Usage of Ti 3 C 2 T x and Mo 2 TiC 2 T x nanosheets as additives in synovial fluid. • Stable colloidal solutions in different concentrations. • Add MXenes alternate wettability and reduce dynamic viscosity. • Friction reduction and up to 77 % wear reduction for 5 mg/mL Ti 3 C 2 T x . • Improved biotribological behavior attributed to tribo-film formation. Synovial joints, critical for limb biomechanics, rely on sophisticated lubrication systems to minimize wear. Disruptions, whether from injury or disease, often necessitate joint replacements. While additive manufacturing offers personalized implants, ensuring wear resistance remains a challenge. This study delves into the potential of Ti 3 C 2 T x and Mo 2 TiC 2 T x nanosheets in mitigating wear of additively manufactured cobalt-chromium tungsten alloy substrates when incorporated as additives into synovial fluid. The colloidal solutions demonstrate an excellent stability, a crucial factor for reproducible assays and potential clinical applicability. Analysis of contact angles and surface tensions reveals MXene-induced alterations in substrate wettability, while maintaining their general hydrophilic character. Viscosity analysis indicates that MXene addition reduces the dynamic viscosity, particularly at higher concentrations above 5 mg/mL, thus enhancing dispersion and lubrication properties. Friction and wear tests demonstrate a dependency on the MXene concentration, while Ti 3 C 2 T x exhibits stable friction coefficients and up to 77 % wear reduction at 5 mg/mL, which was attributed to the formation of a wear-protecting tribo-film (amorphous carbon and MXene nano-sheets). Our findings suggest that Ti 3 C 2 T x , when supplied in favorable concentrations, holds promise for reducing wear in biotribological applications, offering avenues for future research into optimizing MXene utilization in load-bearing joint replacements and other biomedical devices.